SA rail, roads net millions from the feds

South Australia's $1.8 billion share of federal budget infrastructure funding - to be used on rail and road works - has been welcomed by state treasurer Rob Lucas.

A total of $1.4 billion was set aside to finish the South Road upgrade, in a bid to make good on a coalition promise to rebuild the corridor by 2023.

That figure includes $177 million for upgrading the Pym Street to Regency Road stretch between Gawler and the River Torrens, and $1.2 billion for future sections.

As expected, the state will receive $220 million for the electrification of the Gawler rail line.

"Current services on the Gawler rail line are reaching capacity and will be unable to support future demand," budget papers say.

The budget also allocated $160 million for the Joy Baluch bridge in Port Augusta - an improvement to the national freight network.

Mr Lucas said the state had received its fair share of funding, but still needed to work through some issues with the federal government.

"Of the $24.5 billion of new (infrastructure) expenditure, our total expenditure of $1.8 billion is about our national population share of seven per cent, so obviously we welcome that," he told AAP on Tuesday night.

"The critical issue for us will be in terms of the timing of the various payments over the forward estimates period and beyond the forward estimates."

South Australia's GST allocation will increase from $6.37 billion this year to $6.89 billion in 2018-19, representing a 10.3 per cent share of the national pool.

"We're also glad to see that the national growth in the economy has led to an increase in the GST pool, which means that all states will see an increased benefit in terms of their shares," Mr Lucas said.

"Our position continues to be very strongly that we'll fight any proposed changes that lead to cuts in proposed GST revenue to South Australia."

WHAT'S IN THE BUDGET FOR SOUTH AUSTRALIA

* $1.4 billion for the North-South Road corridor projects, including $177 million for the Regency Road to Pym Street

* $220 million for electrify the Gawler rail line from Salisbury to Gawler

* $160 million for the Joy Baluch bridgeAs expected, the state will receive $220 million for the electrification of the Gawler rail line.

"Current services on the Gawler rail line are reaching capacity and will be unable to support future demand," budget papers say.

The budget also allocated $160 million for the Joy Baluch bridge in Port Augusta - an improvement to the national freight network.

Mr Lucas said the state had received its fair share of funding, but still needed to work through some issues with the federal government.

"Of the $24.5 billion of new (infrastructure) expenditure, our total expenditure of $1.8 billion is about our national population share of seven per cent, so obviously we welcome that," he told AAP on Tuesday night.

"The critical issue for us will be in terms of the timing of the various payments over the forward estimates period and beyond the forward estimates."

South Australia's GST allocation will increase from $6.37 billion this year to $6.89 billion in 2018-19, representing a 10.3 per cent share of the national pool.

"We're also glad to see that the national growth in the economy has led to an increase in the GST pool, which means that all states will see an increased benefit in terms of their shares," Mr Lucas said.

"Our position continues to be very strongly that we'll fight any proposed changes that lead to cuts in proposed GST revenue to South Australia."

WHAT'S IN THE BUDGET FOR SOUTH AUSTRALIA

* $1.4 billion for the North-South Road corridor projects, including $177 million for the Regency Road to Pym Street

* $220 million for electrify the Gawler rail line from Salisbury to Gawler